Apply, a, is a command to 'use' an item. For example, you can apply a unicorn horn to remedy confusion, blindness, sickness, etc. You can also apply a pick-axe to break down a wall, a lamp to light it, a magic marker to write, etc.
Most weapons are used by throwing, firing, or by first wielding and then attempting to walk into an opponent. The exception is polearms, which must be wielded, then applied from exactly two squares away. See the article on pounding for details.
Artifacts may have powers that can be accessed by the apply command, and may have additional powers that can be accessed by the invoke command. See, for example the Orb of Fate, which acts as a crystal ball when applied and provides level teleportation when invoked.
- You can identify the potion of oil by trying to apply each unidentified potion: the potion of oil will ignite.
- You can identify each type of horn by applying it. Do this in a safe place where awakening nearby monsters or shooting beams of fire and ice will not cause problems.
- Apply a whistle; if "You produce a high whistling sound" then it is a tin whistle, but if "You produce a strange whistling sound" then it is a magic whistle. You might see other messages if the whistle is cursed or you are hallucinating.